Most widely used Solid State Drives (SSDs) support single port Input/Output (I/O). Some SSDs support dual port I/O for higher system availability by offering better fault protection. But dual port devices are generally more expensive and may have slightly lower performance (if the amount of information to be sent exceeds the capacity of the bus used to transfer the information). Ethernet attached SSDs or Non-Volatile Memory Express (NVMe) Over Fabrics (NVMeoF) devices are considered new, emerging, and disruptive technology. Such devices may have different types, but would fall under either single port or dual port I/O devices.
But while single port I/O devices are less expensive and may offer better performance, single port I/O devices do have a weakness: the chassis only uses one path to communicate with the device. If any component along this path should fail, the device (and more importantly, any data on the device) will be inaccessible until the fault is corrected or the system performs a graceful recovery.
A need remains for a way for to provide access to single port devices in the event of a failure along the path between the device and its chassis.